Get rid of Edit PS CS6 in LR4?

Edit in Photo Shop is a permanent part of LR. I don't have PS on my computer yet since installing a new OS. Edit in Photo Shop is still there although grayed out. You have the option of adding another external editor of your choice such as Paint Shop Pro in preferences / external editor.

All your other plug-ins are found in the File / Plug-in Extras.

You should be able to delete the plug-in from one of LRs folders to make it grayed out if it bothers you.